[PATCH v2 7/8] hwtracing: hisi_ptt: Add pattern PMU config for trace format selection

[Sizhe Liu <liusizhe5@huawei.com>]

Introduce a `pattern` PMU config field (config:36-39) that controls
which TLP header format the hardware traces. bit[3:1] are reserved for
future extension and only bit0 is used currently:

- pattern=0 (default, compatibility mode): the driver sets bit[8] of
  HISI_PTT_TRACE_CTRL so the hardware traces the data in compatibility
  mode.
- pattern=1: the driver clears bit[8] of HISI_PTT_TRACE_CTRL so the
  hardware traces the data pattern including some bitfields of the TLP
  header defined in PCIe r6.4 sec 2.2.1.2.

Note that bit[8] of HISI_PTT_TRACE_CTRL is inverted with respect to the
`pattern` value: bit[8]=1 selects the legacy format, bit[8]=0 selects
the new format. Bit[11:9] is still reserved, which is consistent with the
PMU config field. The driver validates the 4-bit value in
hisi_ptt_trace_valid_pattern() and applies it in hisi_ptt_trace_start().

Document the new parameter in Documentation/trace/hisi-ptt.rst.

Signed-off-by: Sizhe Liu <liusizhe5@huawei.com>
---
 Documentation/trace/hisi-ptt.rst | 25 +++++++++++++++++++++++--
 drivers/hwtracing/ptt/hisi_ptt.c | 25 ++++++++++++++++++++++++-
 drivers/hwtracing/ptt/hisi_ptt.h |  4 ++++
 3 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/Documentation/trace/hisi-ptt.rst b/Documentation/trace/hisi-ptt.rst
index f6a2655f99e5..c95eaa12f4d3 100644
--- a/Documentation/trace/hisi-ptt.rst
+++ b/Documentation/trace/hisi-ptt.rst
@@ -255,7 +255,28 @@ directly from the TLP header.
      DW2 [                     Header DW2                            ]
      DW3 [                     Header DW3                            ]
 
-5. Memory Management
+5. Trace pattern
+-----------------
+
+You can control whether the trace is taken with the new version of the
+TLP header format by specifying the `pattern` parameter. The default
+value is 0, which means the legacy format is used for backward
+compatibility. The parameter value is 4 bit and bit[3:1] are currently
+reserved for extension. Current supported values are shown below:
+
+- 4'b0000: legacy trace format
+    DW2 and DW3 are printed with generic field names only, and
+    no message-type-basedfield decoding.
+- 4'b0001: trace format v1
+    DW2 and DW3 are decoded according to the TLP message type (MWr,
+    Msg, Atomic, IO, CPL, Cfg) with detailed field names. It is recommended to
+    use trace format v1 when the current PCIe link generation is higher than
+    PCIe 6.0.
+
+For trace data recorded by an older tracer without the `pattern` parameter,
+the decoder will work as `pattern` forced to 0.
+
+6. Memory Management
 --------------------
 
 The traced TLP headers will be written to the memory allocated
@@ -274,7 +295,7 @@ will commit the AUX buffer first and then apply for a new one with
 the same size. The size of AUX buffer is default to 16MiB. User can
 adjust the size by specifying the `-m` parameter of the perf command.
 
-6. Decoding
+7. Decoding
 -----------
 
 You can decode the traced data with `perf report -D` command (currently
diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
index 94c371c49135..1696c30ac4c9 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.c
+++ b/drivers/hwtracing/ptt/hisi_ptt.c
@@ -233,6 +233,10 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
 	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
 	if (!hisi_ptt->trace_ctrl.is_port)
 		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
+	if (!ctrl->pattern)
+		val |= HISI_PTT_TRACE_CTRL_PATTERN;
+	else
+		val &= ~HISI_PTT_TRACE_CTRL_PATTERN;
 
 	/* Start the Trace */
 	val |= HISI_PTT_TRACE_CTRL_EN;
@@ -805,12 +809,14 @@ PMU_FORMAT_ATTR(filter,		"config:0-19");
 PMU_FORMAT_ATTR(direction,	"config:20-23");
 PMU_FORMAT_ATTR(type,		"config:24-31");
 PMU_FORMAT_ATTR(format,		"config:32-35");
+PMU_FORMAT_ATTR(pattern,		"config:36-39");
 
 static struct attribute *hisi_ptt_pmu_format_attrs[] = {
 	&format_attr_filter.attr,
 	&format_attr_direction.attr,
 	&format_attr_type.attr,
 	&format_attr_format.attr,
+	&format_attr_pattern.attr,
 	NULL
 };
 
@@ -940,6 +946,15 @@ static int hisi_ptt_trace_valid_format(u32 val)
 	return -EINVAL;
 }
 
+static int hisi_ptt_trace_valid_pattern(u32 val)
+{
+	/* Currently only bit0 is used, bit[3:1] are reserved for extension. */
+	if (val <= 1)
+		return 0;
+
+	return -EINVAL;
+}
+
 static int hisi_ptt_trace_valid_filter(struct hisi_ptt *hisi_ptt, u64 config)
 {
 	unsigned long val, port_mask = hisi_ptt->port_mask;
@@ -990,6 +1005,9 @@ static void hisi_ptt_pmu_init_configs(struct hisi_ptt *hisi_ptt, struct perf_eve
 
 	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
 	ctrl->format = val;
+
+	val = FIELD_GET(HISI_PTT_PMU_PATTERN_MASK, event->attr.config);
+	ctrl->pattern = val;
 }
 
 static int hisi_ptt_pmu_event_init(struct perf_event *event)
@@ -1024,7 +1042,12 @@ static int hisi_ptt_pmu_event_init(struct perf_event *event)
 		return ret;
 
 	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
-	return hisi_ptt_trace_valid_format(val);
+	ret = hisi_ptt_trace_valid_format(val);
+	if (ret < 0)
+		return ret;
+
+	val = FIELD_GET(HISI_PTT_PMU_PATTERN_MASK, event->attr.config);
+	return hisi_ptt_trace_valid_pattern(val);
 }
 
 static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
diff --git a/drivers/hwtracing/ptt/hisi_ptt.h b/drivers/hwtracing/ptt/hisi_ptt.h
index 46030aa88081..584f65ba1e32 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.h
+++ b/drivers/hwtracing/ptt/hisi_ptt.h
@@ -41,6 +41,7 @@
 #define   HISI_PTT_TRACE_CTRL_RST	BIT(1)
 #define   HISI_PTT_TRACE_CTRL_RXTX_SEL	GENMASK(3, 2)
 #define   HISI_PTT_TRACE_CTRL_TYPE_SEL	GENMASK(7, 4)
+#define   HISI_PTT_TRACE_CTRL_PATTERN	BIT(8)
 #define   HISI_PTT_TRACE_CTRL_DATA_FORMAT	BIT(14)
 #define   HISI_PTT_TRACE_CTRL_FILTER_MODE	BIT(15)
 #define   HISI_PTT_TRACE_CTRL_TARGET_SEL	GENMASK(31, 16)
@@ -89,6 +90,7 @@
 #define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
 #define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
 #define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
+#define HISI_PTT_PMU_PATTERN_MASK	GENMASK(39, 36)
 
 /**
  * struct hisi_ptt_tune_desc - Describe tune event for PTT tune
@@ -127,6 +129,7 @@ struct hisi_ptt_dma_buffer {
  * @filter:    filter value for tracing the TLP headers
  * @format:    format of the TLP headers to trace
  * @type:      type of the TLP headers to trace
+ * @pattern:   pattern of the TLP headers to trace
  */
 struct hisi_ptt_trace_ctrl {
 	struct hisi_ptt_dma_buffer *trace_buf;
@@ -139,6 +142,7 @@ struct hisi_ptt_trace_ctrl {
 	u32 filter:16;
 	u32 format:1;
 	u32 type:4;
+	u32 pattern:1;
 };
 
 /*
-- 
2.33.0